1. Field of the Invention
The present invention relates to a cleaning device suitable for cleaning a floor surface of a house, an office, etc., and more particularly to a cleaning device which can be stably slid on an object to be cleaned, such as a floor surface, to improve its cleaning ability.
2. Description of the Related Art
Cleaning devices to be used with a replaceable or disposable cleaning sheet are typically constructed to include a cleaning head, to which the cleaning sheet is to be attached, and a shaft-like handle whose front end is connected to the cleaning head.
In such cleaning devices, if the cleaning head has a flat bottom face, the cleaning sheet attached to the cleaning head will be applied to a surface to be cleaned (e.g., floor surface) with the flat bottom face in face-to-face relationship with the floor surface. When the floor surface is wiped off, dirt or dust will attach to the exterior surface of the cleaning sheet not centrally of the bottom face but around the front and rear edges of the bottom face. Therefore, the cleaning sheet cannot be fully exploited.
On the other hand, cleaning devices whose cleaning head has an uneven bottom face are disclosed in the following patent publications.
Japanese Patent Registration No. 2930472 discloses a cleaning head which has slopes along the front and rear ends of the bottom face to project toward the floor surface midway between the front and rear ends of the bottom face. Japanese Patent Registration No. 2981110 discloses a cleaning head which increases stepwise in thickness with distance from the front and rear ends of the bottom face to project toward the floor surface midway between the front and rear ends of the bottom face. Japanese Unexamined Patent Publication No. H11-244210 discloses a cleaning head whose bottom face is convexly curved, as viewed from the side, to project toward the floor surface midway between the front and rear ends of the bottom face. Japanese Unexamined Patent Publication No. 2004-33530 discloses a cleaning head whose bottom face is convexly curved, as viewed from the side (in the same manner as disclosed in Patent Publication H11-244210), but is also recessed midway between the right and left ends as viewed from the front to diverge from the floor surface.
In the cleaning devices disclosed in the above-identified Patent Publications, a shaft-like handle is connected to the cleaning head midway between the front and rear ends. When the cleaning head is slid forward on the floor surface by holding the handle, therefore, the front end of the cleaning head is pressed against the floor surface with a force exerted by the handle.
Since the cleaning heads disclosed in the above-identified Patent Publications have a bottom face which projects toward the floor surface midway between the front and rear ends and which diverges from the floor surface toward the front and rear ends, when the cleaning head is moved forward with the handle pushed by hand, therefore, the cleaning head tends to be inclined forward and pressed against the floor surface in an unstable position, which results in inefficient transmission of the force pushing the handle to the cleaning head and also results in increasing the resistance to sliding of the cleaning head along the floor surface.
If the cleaning head slides on the floor surface in a forwardly inclined position, the dirt or dust tends to attach to the cleaning sheet around the front end of the cleaning head, while the cleaning sheet remains unexploited around the rear end of the cleaning head.
In the cleaning head disclosed in Patent Publication No. 2004-33530, however, the dirt or dust can be relatively easily directed to the center of the bottom face because a recess is formed in the bottom face midway between the right and left ends. In addition, since the contact area between the cleaning head and the floor surface can be substantially decreased, the friction against the floor surface can also be decreased.
However, since the recess is formed in the bottom face to extend continuously from the front edge to the rear edge, the dirt or dust cannot be sufficiently collected by the cleaning sheet beneath the recess.